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522.6.1 Impact (AG).

Zoomup
Have you every said: " I haven't got a grommet or bush so I'll just run the cable through the sharp edged metal hole anyway. It'll be O.K?"


Well, 522.6.1 says: "Wiring systems shall be selected and erected so as to minimise the damage arising from mechanical stress, e.g. by ABRASION, PENETRATION, TENSION, or COMPRESSION, during installation, use or maintenance."


The old familiar expression comes to mind: for the want of a nail the horseshoe was lost, and its following disastrous consequences. For the want of a grommet, materials and correct installation lives were lost.

https://www.youtube.com/watch?v=Ql16ggFvc_g


Z.


  • 0
    This is very very unlikely to cause loss of life Z. The backbox or fuse enclosure or whatever is Earthed exactly so that if a conductor contacted it would trip/blow the CPD. Much more likely is threading T&E through holes in walls and inadequate fixings so that it rubs WITH MOVEMENT during the installation life. You really ought to get a degree of realism here and stop stressing yourself unnecessarily as death will be closer than you think due to heart or brain problems. Just relax a little! Perhaps the staying in and watching youtube is getting to you, why not try testing every RCD you have with some added DC and letting me have the results, it is quite a long job?
  • 0
    davezawadi:

    This is very very unlikely to cause loss of life Z. The backbox or fuse enclosure or whatever is Earthed exactly so that if a conductor contacted it would trip/blow the CPD. Much more likely is threading T&E through holes in walls and inadequate fixings so that it rubs WITH MOVEMENT during the installation life. You really ought to get a degree of realism here and stop stressing yourself unnecessarily as death will be closer than you think due to heart or brain problems. Just relax a little! Perhaps the staying in and watching youtube is getting to you, why not try testing every RCD you have with some added DC and letting me have the results, it is quite a long job?


    The video clip emphasises the need to attend to detail to prevent danger. Did you watch it? If not then you do not have the complete picture.


    I agree that a chaffed cable may not lead to death directly, but if it leads to a loss of supply then who knows what may happen if essential equipment is disconnected. You have missed the point of my post entirely.


    Z.


  • 0
    The take I got from that video were that two astonishing deficiencies combined to cause the loss of the aircraft. First, that the metallised mylar sheets were highly flammable, yet were still approved for airliner use. Second, that there was no requirement for loose unsheathed cable runs to be protected from rubbing against metallic guides, given the vibration and shaking that an airliner is liable to experience over its lifetime. Hopefully things have improved since them.
  • 0
    Rose park Care Home January 2004. Fourteen dead. Ignition source; arcing where cable passed through knockout in distribution board. No grommet fitted.

    Of course as the introduction to the video indicates, it normally takes a series of things to go wrong. Nonetheless, rare as it might be, really important to properly secure cables and protect them as they pass through knockouts to guard against potential arcing.
  • 0
    lyledunn:

    Rose park Care Home January 2004. Fourteen dead. Ignition source; arcing where cable passed through knockout in distribution board. No grommet fitted.

    Of course as the introduction to the video indicates, it normally takes a series of things to go wrong. Nonetheless, rare as it might be, really important to properly secure cables and protect them as they pass through knockouts to guard against potential arcing.


    The fire started in a cupboard along a corridor, following an electrical fault. It is thought that aerosols stored in the cupboard exploded, the force of the blast blowing open some nearby fire doors along the corridor. Materials immediately outside the cupboard – chairs, wallpaper, timber handrails – ignited, causing heat and smoke to spread.


    A terrible avoidable tragedy.


    Z.


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